Mauna Loa Update

Last October I posted an article on Mauna Loa. As an update, below is an advisory issued by the Hawaiian Volcano Observatory today.


HVO/USGS Volcanic Activity Notice

Volcano: Mauna Loa (VNUM #332020)

Current Volcano Alert Level: ADVISORY
Previous Volcano Alert Level: NORMAL

Current Aviation Color Code: YELLOW
Previous Aviation Color Code: GREEN

Issued: Thursday, September 17, 2015, 1:29 PM PDT (20150917/2029Z)
Source: Hawaiian Volcano Observatory
Notice Number: 2015/H2
Location: N 19 deg 28 min W 155 deg 36 min
Elevation: 13681 ft (4170 m)
Area: HI Hawaii and Pacific Ocean

Volcanic Activity Summary: HVO seismic stations continue to record elevated rates of shallow, small-magnitude earthquakes beneath Mauna Loa’s summit, upper Southwest Rift Zone, and west flank. For at least the past year, the rate of shallow earthquakes has varied but overall has remained above the long-term average. During this same time period, HVO has measured ground deformation consistent with recharge of the volcano’s shallow magma storage system. Together, these observations indicate the volcano is no longer at a background level of activity. Accordingly, HVO is elevating the Mauna Loa alert level to ADVISORY and the aviation color code to YELLOW.

This increase in alert level does not mean that an eruption is imminent or that progression to an eruption is certain.

Shallow earthquakes are occurring in locations similar to those that preceded Mauna Loa's two most recent eruptions in 1975 and 1984; however, the energy release of the recent earthquakes remains comparatively low. The current rate and pattern of ground deformation is similar to that measured during inflation of Mauna Loa in 2005, an episode of unrest that did not end in an eruption.

It is possible that, as in 2005, the present heightened activity will continue for many months, or even years, without progressing to an eruption. It is also possible that the current unrest is a precursor to an eruption, as was the case prior to eruptions in 1975 and 1984. At this early stage of unrest, we cannot determine which of these possibilities is more likely.

HVO continues to monitor the volcano closely and will report any significant changes.

Stay informed about Mauna Loa by following volcano updates and tracking current monitoring data on the HVO web page (http://hvo.wr.usgs.gov/activity/maunaloastatus.php) or by signing up to receive updates by email at this site: http://volcanoes.usgs.gov/vns/